Method of forming sheet having foreign material portions used for forming multi-layer wiring board and sheet having foreign portions

ABSTRACT

The present invention relates to a laminated type electronic part and aims at providing a sheet manufacturing method and a sheet that contribute to high integration, downsizing and enhancement of reliability of the electronic part. To accomplish this object, the manufacturing method according to the present invention involves forming a layer composed of a positive resist on a support body, repeatedly executing an exposure process, a developing process and a depositing process of depositing a substance having a desired electrical characteristic into an obtained pattern space with respect to the layer, and thereafter removing the support body. The sheet composed of portions, having three or more types of different physical properties, of which an aspect ratio in pattern is equal to or larger than 1, is provided by this manufacturing method.

TECHNICAL FIELD

The present invention relates to, as typified by a laminated inductorand a laminated capacitor, a laminated type electronic part exemplifiedby a so-called multi-layered wiring substrate having built-in passivecomponents etc. The present invention relates more particularly to aso-called ceramic green sheet used when manufacturing the multi-layeredwiring substrate and to a method of manufacturing the single ceramicgreen sheet including portions composed of a variety of materials.

BACKGROUND ARTS

Over the recent years, with higher performance of electronic devices, orwith the rapid spread of portable devices, electronic parts arerequested to have an improvement of high frequency characteristicstogether with high-density packaging. What is examined to respond such arequest is a manufacturing method capable of attaining a hyperfineelement or high-accuracy manufacturing in the process of producing theelectronic parts. Documents disclosing these methods are given such asJapanese Patent Application Laid-Open No. 2001-85264, Japanese PatentApplication Laid-Open No. 2001-110662, Japanese Patent ApplicationLaid-Open No. 2001-76959, Japanese Patent Application Laid-Open No.2000-331858, Japanese Patent Application Laid-Open No. 2000-331865,Japanese Patent Application Laid-Open No. 2001-111223, Japanese PatentApplication Laid-Open No. 2000-183530, and Japanese Patent ApplicationLaid-Open No. 10-12455.

For instance, the manufacturing method will be briefly described byexemplifying a so-called laminated ceramic inductor as the electronicpart. To begin with, a slurry obtained by mixing ceramic powderexhibiting a predetermined electrical characteristic with an organicbinder is coated thick over a support body such as a PET film. On thethus-acquired insulator layer, metal paste composed of the metal powderand the organic binder is further printed in a predetermined pattern,thus forming an electrode layer. This electrode layer configures part ofthe inductor body of the ceramic inductor.

A sheet including the inductor of which part is formed on thethus-acquired insulator and a sheet composed of only the insulator arelaminated. On this occasion, respective electrode layers on theindividual sheets are electrically connected through conductive portions(posts) provided inside the insulator sheets, thereby forming alaminated body serving as the ceramic inductor body. After forming thelaminated body, the laminated ceramic inductor is acquired by furtherexecuting processes such as sintering and forming an end face electrode.The method of manufacturing the laminated type electronic part etc.other than the ceramic inductor also basically involves conducting astep pursuant to the aforementioned manufacturing step.

In the aforementioned manufacturing method, however, there occurs alimit to providing the electronic part having the higher performance dueto scatters in shape and thickness of each layer, a scatter in shrinkageratio when sintering, etc. Such being the case, the present applicantproposes the electronic part manufacturing method as disclosed inJapanese Patent Application Laid-Open No. 2001-85264 or Japanese PatentApplication Laid-Open No. 2001-110662 given above, thus trying tocorrespond to the high performance requested of the electronic part.

For example, Japanese Patent Application Laid-Open No. 2001-85264discloses a method of manufacturing the so-called laminated ceramiccapacitor as one of the electronic parts. In this manufacturing method,specifically, to start with, a photosensitive slurry obtained by mixingthe organic binder exhibiting photosensitivity and the ceramic powder iscoated to a predetermined thickness over the surface of the support bodysubjected to a conductive process beforehand. It is to be noted thatthis photosensitive slurry may also be formed by an electro-depositingtechnology. Subsequently, the photosensitive slurry undergoes anexposure process based on ultraviolet rays via a photomask and adeveloping process using a developer, whereby a layer constructed of aspatial portion and a ceramic portion is formed on the support body.

Herein, an eutectoid layer composed of Ni powder and an acrylic resin isdeposited by the electro-depositing technology on this spatial portionto a thickness that is substantially the same as a thickness of theceramic portion. The thus-acquired sheet constructed of the ceramicportion and the eutectoid layer portion containing the Ni powder isexfoliated from the support body as an integral body and is subjected tothe processes such as laminating, sintering and forming the end faceelectrode, thereby obtaining the laminated ceramic capacitor. Further,Japanese Patent Laid-Open No. 2001-110662 discloses a method of formingthe so-called laminated ceramic inductor, wherein this manufacturingmethod deals with forming the ceramic portion and the spatial portion onthe support body, forming the eutectoid layer containing Ag powder overthe spatial portion, and so on.

According to the electronic part manufacturing method disclosed inJapanese Patent Application Laid-Open No. 2001-85264 or Japanese PatentApplication Laid-Open No. 2001-110662 given above, there is nodifference in layer thickness between the ceramic portion and theeutectoid layer in the sheet itself formed on the support body, i.e.,these thicknesses are substantially uniform. Hence, as compared with theconventional method of laminating the simple ceramic pattern and thesimple electrode pattern, there is a small change in the electricalcharacteristic due to the sintering process etc., and it follows thatthe electronic part exhibiting a desired electrical characteristic isobtained with high reproducibility.

At the present, a frequency of a signal used for the electronic deviceetc. becomes as high as a GHz band, and, for gaining flexibility to therise in frequency, much higher performance such as decreasingcapacitance of a transmission line and reducing resistance at a joiningportion is also desired of the above-described electronic part etc. Atthe same time, further high integration and further downsizing aredesired for being provided to the portable terminals. As for the sheetobtained by the aforementioned manufacturing method, it is consideredthat, for instance, the flexibility to some extent can be attained bymaking advance in parallel with thinning the layer and optimizing thematerial such as the conductive paste.

The sheet acquired by the manufacturing method described above is,however, merely made from the two types of materials, i.e., the ceramicportion and the eutectoid layer portion. Accordingly, a restriction thatthe single sheet be constructed of the single type of insulator and thesingle type of conductor, is always imposed in terms of manufacturingthe electronic part. As a result, it is considered that there might beincurred situations such as 1) causing a restriction in the circuitdesign and hindering the high integration from a certain level, 2)extremely increasing the number of layers to be laminated and hinderingthe downsizing from a certain level in the case of forming theelectronic part including, e.g., the inductor, and 3) causing apossibility that the reliability decreases due to an increase in thenumber of layer-to-layer connecting portions as the number of layersincreases.

Moreover, the photosensitive slurry is, as explained earlier, acquiredby mixing the organic binder having the photosensitivity with theceramic powder. The ceramic powder normally has an effect of diffusingthe ultraviolet rays when in exposure. Therefore, there occurs aphenomenon such as blurring in pattern edge when exposed. As aconsequence, in the prior art, when a ratio of a thickness to a width ofthe wiring pattern to be formed is set as an aspect ratio(thickness÷width), its upper limit is approximately 0.5 through 0.67.

Japanese Patent Application Laid-Open No. 2001-110662 discloses a methodfor corresponding to this condition. To be specific, a layer composed ofonly a negative resist formed on a base (substrate) is subjected topatterning, a ceramic portion is formed in a space formed after thepatterning by employing the electro-depositing technology, aresist-layer undergoing the patterning is removed, and a portionexhibiting conductivity is formed by the electro-depositing technologyin a spatial portion formed after the removal.

According to this method, none of the blur occurs at the pattern edgedescribed above, and hence the sheet having high pattern accuracy can beformed. The restriction that the single sheet be constructed of thesingle type of insulator and the single type of conductor is, however,still always imposed on even this method. Accordingly, a probabilitythat the situations given in the items 1) through 3) described above is,it is considered, the same with this method.

DISCLOSURE OF THE INVENTION

It is an object of the present invention, which was devised in view ofthe conditions described above, to provide a method of manufacturing asheet capable of contributing to high integration, downsizing, highreliability, etc. with respect to a so-called laminated type electronicpart such as a laminated ceramic capacitor and a laminated ceramicinductor.

To accomplish the object, a sheet forming method according to thepresent invention is a sheet forming method of forming a sheet used aseach layer when forming a laminated type electronic part, comprising astep of depositing a photosensitive substance of which an exposedportion is removed by a developer up to a predetermined thickness onto asupport body, a step of executing an exposure process for forming apredetermined pattern upon the photosensitive substance, executing aprocess for development-removing the pattern subjected to the exposureprocess by use of the developer, executing a process of depositing asubstance having a desired electrical characteristic onto the portionwith the photosensitive substance removed, and forming the sheet or partof the sheet on the support body, and a step of removing the supportbody from the sheet.

It should be noted that in the aforementioned method, the stepconsisting of the exposure process, the developing process and thedepositing process is, it is preferable, repeated plural number oftimes. Moreover, in the above-described method, it is preferable thatthe step consisting of the exposure process, the developing process andthe depositing process includes a process of depositing thephotosensitive substance in place of the substance having the desiredelectrical characteristic.

Further, it is preferable that the method described above furthercomprises a step of depositing a photosensitive substance, having adesired electrical characteristic, of which an unexposed portion isremoved by the developer, and a step consisting of a process of forminga further pattern space by exposing and developing the photosensitivesubstance having the desired electrical characteristic, and a process ofdepositing the substance having the desired electrical characteristic ora further photosensitive substance into the pattern space.

To accomplish the above object, a sheet according to the presentinvention is a sheet used as each layer when forming a laminated typeelectronic part, comprising a portion having at least three types ofdifferent physical properties, wherein when forming the portion, thereare executed a depositing process of depositing a photosensitivesubstance of which an exposed portion is removed by a developer, anexposure process of exposing the photosensitive substance, a developingprocess of developing the photosensitive substance, and at least onedeposition-forming process of the portion into a spatial portionobtained by the developing process, and, when a ratio of a thickness toa width of a thickest portion in the portion is set as an aspect ratio(thickness÷width), a value of the aspect ratio is equal to or largerthan 1.

It should be noted that in the aforementioned sheet, portions exhibitingdifferent physical properties are, it is preferable, respectively formedin a direction of a plane on which the sheet extends. Further, it ispreferable that in the aforementioned sheet, the portions exhibitingdifferent physical properties are formed in a thicknesswise direction ofthe sheet.

To accomplish the above object, a sheet according to the presentinvention is a sheet used as each layer when forming a laminated typeelectronic part, comprising a conductive internal electrode having afirst thickness and formed in a first area, a conductive post having asecond thickness and formed in a second area existing over the firstarea and smaller than the first area, and an insulating substanceincluding the internal electrode and the post, wherein at least the postis formed by a step consisting of a depositing process of depositing aphotosensitive substance of which an exposed portion is removed by adeveloper, an exposure process of exposing the photosensitive substance,a developing process of developing the photosensitive substance, and adepositing process of depositing of a conductive substance into aspatial portion obtained by the developing process, and, when a ratio ofa forming thickness to a width of at least one of the internal electrodeand the post is set as an aspect ratio (thickness÷width), a value of theaspect ratio is equal to or larger than 1.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart showing a sheet forming method according to thepresent invention;

FIG. 2 is a flowchart showing the sheet forming method according to thepresent invention;

FIG. 3 is a view schematically showing a section of a laminated typeinductor manufactured by use of the sheet obtained by the presentinvention;

FIG. 4A is a view of the inductor shown in FIG. 3 that is cut along theline 4A-4A and showing an outline of a state as viewed from an uppersurface;

FIG. 4B is a view of the inductor shown in FIG. 3 that is cut along theline 4B-4B and showing an outline of a state as viewed from an uppersurface;

FIG. 5A is a flowchart showing steps of forming a sheet L4 shown in FIG.3;

FIG. 5B is a flowchart showing steps of forming the sheet L4 shown inFIG. 3; and

FIG. 5C is a flowchart showing steps of forming the sheet L4 shown inFIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a flowchart showing a sheet forming method according to anembodiment of the present invention. Note that FIG. 1 illustratesprofiles of the sheet in section in respective steps when cut in athicknesswise direction thereof. It is assumed that the sheetexemplified has defined portions composed of materials different fromeach other in an X-Y (plane) direction and a Z (thickness) direction.The sheet forming method will hereinafter be described in depth withreference to the drawings.

To begin with, a layer 3 composed of a positive resist is formed to apredetermined thickness by an electro-depositing process on a surface ofa support body 1 subjected to a conductive process, thereby obtaining asheet in a state in step 1. It should be noted that the positive resistaccording to the present invention represents a photosensitive substanceof which a portion exposed to irradiation of light is removed by adeveloping process using a developer. Subsequently, there are executedan exposure process of the positive resist layer 3 by ultraviolet raysetc. through an unillustrated first mask and the developing processusing the developer. Through the processes described above, only theexposed portion on the positive resist layer 3 is removed, and theunexposed positive resist layer 3 and a first spatial portion 5 areformed on the support body 1 (step 2). An insulator portion is formed bythe electro-depositing process in the first spatial portion 5. In thepresent embodiment, a portion 7 composed of an insulating material,e.g., a lower dielectric constant material is formed (step 3). Note thata forming thickness of the low dielectric constant material portion 7 isapproximately coincident with the thickness of the positive resist layer3.

After forming the low dielectric constant material portion 7, theunexposed positive resist layer 3 is subjected to the exposure processthrough an unillustrated second mask and the developing process usingthe developer. With these processes, the exposed portion on the positiveresist layer 3 is removed, and further a second spatial portion 9 isformed (step 4). A new insulator portion is formed in the second spatialportion 9 by the electro-depositing process. In the present embodiment,as an insulator, for instance, a portion 11 made from a highpermeability material is formed (step 5). Note that in the presentembodiment, a forming thickness of the high permeability materialportion 11 is also approximately coincident with the thickness of thepositive resist layer 3.

Subsequently, the residual unexposed positive resist layer 3 issubjected to the exposure process through an unillustrated third maskand the developing process using the developer. With these processes,the exposed portion on the positive resist layer 3 is removed, andfurther a third spatial portion 13 is formed (step 6). A portion 15composed of a first conductive material is formed by theelectro-depositing process in the third spatial portion 13. Note that inthe present embodiment, when forming the first conductive materialportion 15, its forming thickness is set smaller than the thickness ofthe positive resist layer 3, and the third spatial portion 13 isrendered residual on an upper portion of the first conductive materialportion 15 (step 7).

A second layer 17 composed of a positive resist is again formed on theresidual portion of the third spatial portion 13 by theelectro-depositing process (step 8). On this occasion, the secondpositive resist layer 17 be, it is desirable, formed till its uppermostsurface becomes substantially flush with the surfaces of the positiveresist layer 3, the low dielectric constant material portion 7, etc. Thesecond positive resist layer 17 is subjected to the exposure processthrough an unillustrated fourth mask and the developing process usingthe developer. With these processes, the exposed portion on the secondpositive resist layer 17 is removed, and a fourth spatial portion 19 isformed (step 9).

A further insulator portion is formed in the fourth spatial portion 19by the electro-depositing process. In the present embodiment, as thisinsulator, a portion 21 composed of, e.g., a low permeability materialis formed (step 10). Note that in the present embodiment, the lowpermeability material portion 21 is formed till its uppermost surfacebecomes substantially flush with the surfaces of the positive resistlayer 3, the low dielectric constant material portion 7, etc.Thereafter, the residual second positive resist layer 17 is subjected tothe exposure process and the developing process using the developer.With these processes, the residual second positive resist layer 17 isremoved, and a fifth spatial portion 23 is formed (step 11).

A portion 25 composed of a second conductive material is formed in thefifth spatial portion 23 by the electro-depositing process. Note that inthe present embodiment, the second conductive material portion 25 isformed till its uppermost surface becomes substantially flush with thesurfaces of the positive resist layer 3, the low dielectric constantmaterial portion 7 and so on. Further, in the present embodiment, thematerial composing the first conductive material portion 15 is the sameas the material composing the second conductive material portion 25. Thesupport body 1 is exfoliated from the sheet obtained through theprocesses described above, thereby acquiring a sheet serving as amaterial when actually producing an electronic part.

MODIFIED EXAMPLE

Given subsequently is an explanation of a case in which the sheetforming method according to the present invention is applied to a sheetthat internally has a circuit pattern (simply so-called pattern) and alayer-to-layer connecting material (so-called post). FIG. 2 shows thesheet forming method by way of a flowchart. It is to be noted that theviews indicated by the respective steps in FIG. 2 show the sections(profiles) of the sheet in the individual steps as in the case of FIG.1.

To start with, the layer 3 composed of the positive resist is formed bythe electro-depositing process on the surface of the support body 1subjected to the conductive process, thereby obtaining the sheet in astate of step 1. Subsequently, the exposure process and the developingprocess using the developer are executed on the positive resist layer 3by the ultraviolet rays etc. through the unillustrated first mask. Withthese processes, only the portion exposed on the positive resist layer 3is removed, and the unexposed positive resist layer 3 and the firstspatial portion 5 are formed on the support body 1 (step 2). Theinsulator portion is formed by the electro-depositing process in thefirst spatial portion 5. In the present embodiment, the portion 7composed of the insulating material, e.g., the lower dielectric constantmaterial is formed (step 3). Note that the forming thickness of the lowdielectric constant material portion 7 is approximately coincident withthe thickness of the positive resist layer 3.

After forming the low dielectric constant material portion 7, theunexposed positive resist layer 3 is subjected to the exposure processthrough the unillustrated second mask and the developing process usingthe developer. With these processes, the exposed portion on the positiveresist layer 3 is removed, and further the second spatial portion 9 isformed (step 4). The new insulator portion is formed in the secondspatial portion 9 by the electro-depositing process. In the presentembodiment, as the insulator, for instance, the portion 11 made from thehigh permeability material is formed (step 5). Note that in the presentembodiment, the forming thickness of the high permeability materialportion 11 is also approximately coincident with the thickness of thepositive resist layer 3.

Subsequently, the residual unexposed positive resist layer 3 issubjected to the exposure process through the unillustrated third maskand the developing process using the developer. With these processes,the exposed portion on the positive resist layer 3 is removed, andfurther the third spatial portion 13 is formed (step 6). The portion 15composed of the first conductive material is formed by theelectro-depositing process in the third spatial portion 13. The firstconductive material portion 15 has a function as the pattern in thesheet. Note that in the present embodiment, when forming the firstconductive material portion 15, its forming thickness is set smallerthan the thickness of the positive resist layer 3, and the third spatialportion 13 is rendered residual on the upper portion of the firstconductive material portion 15 (step 7).

The second layer 17 composed of the positive resist is again formed onthe residual portion of the third spatial portion 13 by theelectro-depositing process (step 8). On this occasion, the secondpositive resist layer 17 be, it is desirable, formed till its uppermostsurface becomes substantially flush with the surfaces of the positiveresist layer 3, the low dielectric constant material portion 7, etc. Thesecond positive resist layer 17 is subjected to the exposure processthrough the unillustrated fourth mask and the developing process usingthe developer. With these processes, the exposed portion on the secondpositive resist layer 17 is removed, and the fourth spatial portion 19is formed (step 9).

The further insulator portion is formed in the fourth spatial portion 19by the electro-depositing process. In the present embodiment, as theinsulator, the portion 21 composed of, e.g., the low permeabilitymaterial is formed (step 10). Note that in the present embodiment, thelow permeability material portion 21 is formed till its uppermostsurface becomes substantially flush with the surfaces of the positiveresist layer 3, the low dielectric constant material portion 7, etc.Thereafter, the residual second positive resist layer 17 is subjected tothe exposure process and the developing process using the developer.With these processes, the residual second positive resist layer 17 isremoved, and the fifth spatial portion 23 is formed (step 11).

The portion 25 composed of the second conductive material is formed inthe fifth spatial portion 23 by the electro-depositing process (step12). The second conductive material portion 25 has a function as thepost in the sheet. Note that in the present embodiment, the secondconductive material portion 25 is formed till its uppermost surfacebecomes substantially flush with the surfaces of the positive resistlayer 3, the low dielectric constant material portion 7 and so on.Further, in the present embodiment, the material composing the firstconductive material portion 15 is the same as the material composing thesecond conductive material portion 25. The support body 1 is exfoliatedfrom the sheet obtained through the processes described above, therebyacquiring the sheet having the pattern and the post inside.

As discussed above, the embodiment of the present invention enables theformation of the sheet having the defined portions composed of pluraltypes of materials such as the low dielectric constant material, the lowpermeability material, the high permeability material and the conductivematerial which are equal to or more than three types in this case) inthe X-Y (plane) direction and in the z (thickness) direction or theformation of the sheet having the pattern and the post inside. Further,in the present invention, the layer composed of the single positiveresist containing none of elements that cause scattering of light etc.is subjected to the exposure process and the developing process, and theportions composed of the respective materials are formed by use of thepattern acquired as a result of these processes.

Accordingly, it is possible to acquire the sheet exhibiting a preferabledefined state, wherein pattern accuracy is high, and none of blur etc.exists at a pattern edge. Further, the layer composed of the singlepositive resist is employed, and hence the layer thickness enabling theexposure by the exposure process is attributed to only a characteristicof the positive resist.

Specifically, by use of the methods described above, though impossiblein the prior arts, there are three or more types of portions composed ofdifferent substances, and, in the case of taking, as an aspect ratio(thickness÷width), a ratio of a thickness and a width of the portionthat is thickest among the respective portions, it is possible toprovide the sheet in which the aspect ratio value is equal to or largerthan 1. Moreover, in the case of the sheet including the pattern and thepost, it is feasible to form the sheet including the post in which theratio of the forming thickness to the width thereof is equal to orlarger than 1.

Note that in the present embodiment, the materials composing therespective portions, i.e., the substances exhibiting the desiredelectrical characteristics, involve using the low dielectric constantmaterial, the low permeability material, the high permeability materialand the conductive material, however, the present invention is notlimited to these materials, and it is desirable that the materialsproperly be changed corresponding to the configuration of the sheet tobe acquired. Namely, the portions exhibiting plural types, at least,three types of physical properties different from each other can beformed in the plane direction or in the thicknesswise direction.Accordingly, it is preferable that the number of repetitions of therespective processes such as exposing, developing and electro-depositingbe decreased or increased corresponding to the sheet configuration inthe present embodiment.

Moreover, the aforementioned positive resist or a resist (photosensitivesubstance) exhibiting a positive or negative characteristic thatcontains powder (fine particles) having a desired electricalcharacteristic, may be electro-deposited when executing theelectro-depositing process. In this case, it follows that these resistsfurther undergo the processes such as exposing and developing in thenext step. It should be noted that the negative resist stated hereinrepresents a photosensitive substance, wherein a portion other than theportion exposed to the irradiation of the light is developed by thedeveloper.

To be specific, for example, a negative material obtained by mixinginsulating powder having the low permeability as a characteristic andthe negative resist, may be formed by electro-depositing in the thirdspatial portion 13 in step 7 in FIG. 1. The low permeability materialportion 21 and the fifth spatial portion 23 (refer to step 11) can beformed at one time by effecting the exposure and the development uponthe negative material. As explained earlier, the negative resistcontaining the powder is regarded relatively inferior to the positiveresist with respect to the pattern accuracy etc. In consideration of anallowable value etc. of the pattern accuracy, however, the steps can bereduced in the manufacturing method according to the present inventionby partially employing the material composed of the negative resist.

Further, the forming thickness of each portion based on theelectro-depositing process may not be specified by the thickness of thepositive resist layer 3 as in the present embodiment but can be properlyset corresponding to the configuration etc. of the sheet to be acquired.For instance, when through a laminating/contact bonding step, theforming state of each portion may be altered such as taking aconfiguration that an added conductive material portion is swollen froman upper surface of a ceramic portion 3 in order to make preferable theconnecting state of the conductive material portion between the sheetsto be laminated.

Further, the first and second conductive material portions are made fromthe same material and may also be composed of different materials. Stillfurther, these conductive material portions may be formed by a methoddifferent from the present embodiment such as a plating method etc.without using the electro-depositing process. Yet further, when formingthe conductive material portion, the respective processes such as theelectro-depositing process, the exposing process and the developingprocess of the positive resist and the electro-depositing process of theconductive material are further repeated, and a further configurationmay also be added in the z (thickness) direction.

Specific Example of Electronic Part Manufactured by Use of SheetAcquired according to the Invention

FIG. 3 shows one example of a ceramic inductor formed by laminatingplural types of sheets obtained by properly adding changes to the methodaccording the invention discussed above. FIG. 3 schematically shows aconfiguration in section when cutting the ceramic inductor in alaminating direction. The inductor is constructed by laminating sheetsL1-L8. Each sheet arbitrarily includes conductive material portions A(A1, A2), a first insulator portion B composed of the low dielectricconstant material, second insulator portions C (C1, C2) composed of thehigh permeability material and a third insulator portion D composed of amaterial exhibiting a lower permeability than the second insulatorportion C. Each sheet configuration will hereinafter be brieflyexplained by exemplifying the sheet L4.

In FIG. 3, the sheet L4 is cut by a plane 4A-4A. FIG. 4A shows a view ofthe sheet L4 as viewed in an arrowhead direction in FIG. 4A. FIG. 4Bshows a view of the sheet L4, cut by a plane 4B-4B, as viewed in thearrowhead direction in the FIG. 4B. As illustrated in FIG. 4A, in alower part of the sheet, the central high permeability material portionC1 functions as a core material in the inductor. The conductor materialportion A1 is formed so as to circumscribe approximately a half of theperiphery of the high permeability material portion C1, and configurespart of the inductor circuit.

The low permeability material portion D is formed along the remainingperiphery of the high permeability material portion C1. The insulatorportion D functions as an insulating portion for insulating between theconductive material portions A1 superposed on each other in anup-and-down direction when laminating the sheets. The high permeabilitymaterial portion C2 is disposed along the periphery of the conductivematerial portion A1 and of the low permeability material portion D, andfunctions as an insulator portion having an effect in increasing anamount of magnetic flux together with the high permeability materialportion C1. Further along the periphery of the high permeabilitymaterial portion C2, the first insulator portion B composed of the lowdielectric constant material shapes a protection layer.

As shown in FIG. 4B, in an upper part of the sheet L4, the insulatorportion consisting of the low permeability material portion D is formedso as to circumscribe substantially the entire periphery of the highpermeability material portion C1 serving as the core material. This lowpermeability material portion D functions as an insulating portion forinsulating between the conductive material portions A1 superposed oneach other in the up-and-down direction when laminating the sheets.Further, the conductive material portion A2 is formed along only part ofthe periphery of the core material. The conductive material portion A2,which is the connecting conductive material portion for connectingrespective parts of the circuit in the inductor formed on the individualsheet, functions as a so-called post.

As described above, the sheet L4 internally has the core material, partof the circuit in the inductor formed around approximately the half ofthe periphery of the core material, the post for connecting the part ofthis circuit to part of a circuit on another sheet, the insulatorperforming a role of insulation between the individual circuit portionson the respective sheets, the insulator disposed along the periphery ofthe inductor that increases the amount of magnetic flux together withthe core material, and the protective material portion disposed alongthe periphery thereof. A plurality of sheets each having the aboveconfiguration are manufactured and laminated so that terminal portionsof the circuit portions on the individual sheets are consecutivelyconnected to the terminal portions of the posts, thereby forming theinductor body illustrated in FIG. 3.

Specific Example of Sheet Forming Method for Manufacturing ElectronicPart

Next, the steps of actually forming the sheet L4 shown in FIGS. 4A and4B by utilizing the present invention will be described with referenceto flowcharts shown in FIGS. 5A-5C. Note that the respective views shownin the flowcharts illustrate, as the FIG. 1 or FIG. 2 show, the sectionsof the sheet in the individual steps. To be specific, FIG. 5A shows thesection when the sheet L4 is cut along the line I-I in FIGS. 4A and 4B,FIG. 5B illustrates the section taken along the line II-II, and FIG. 5Cillustrates the section taken along the line III-III, wherein changes inconfiguration are shown, respectively. The same components as those inthe aforementioned embodiment shown in FIG. 1 or FIG. 2 shall be markedwith the same reference numerals and symbols.

At first, the layer 3 composed of the positive resist is formed by theelectro-depositing on the surface of the support body 1 undergoing theconductive process, thereby obtaining the sheet in a state in step 101.Executed subsequently are the exposure process of the positive resistlayer 3 by the ultraviolet rays etc. through the unillustrated firstmask and the developing process using the developer. The first masktakes a shape suited to effecting the exposure over an areacorresponding to the low dielectric constant material portion B in FIGS.4A and 4B.

Through these processes, only the exposed portion on the positive resistlayer 3 is removed, and the unexposed positive resist layer 3 and thefirst spatial portion 5 are formed on the support body 1 (step 102). Theportion 7 composed of the low dielectric constant material is formed bythe electro-depositing process in the first spatial portion 5 (step103). Note that the forming thickness of the low dielectric constantmaterial portion 7 is approximately coincident with the thickness of thepositive resist layer 3. The low dielectric constant material portion 7corresponds to the low electric constant material portion B in the sheetL4.

After forming the low dielectric constant material portion 7, theunexposed positive resist layer 3 is subjected to the exposure processthrough the unillustrated second mask and the developing process usingthe developer. The second mask takes a shape suited to effecting theexposure over an area corresponding to the high permeability materialportions C1 and C2 in FIGS. 4A and 4B. With these processes, the exposedportion on the positive resist layer 3 is removed, and further thesecond spatial portion 9 is formed (step 104).

The portion 11 composed of the high permeability material is formed bythe electro-depositing process in the second spatial portion 9 (step105). Note that the forming thickness of the high permeability materialportion 11 is also approximately coincident with the thickness of thepositive resist layer 3. The high permeability material portion 11 atthe central portion in the section II-II corresponds to the portion C1serving as the core material on the sheet L4, and other parts of thehigh permeability material portion 11 correspond to the portion C2 alongthe outer periphery of the inductor etc. on the sheet L4.

Subsequently, the residual unexposed positive resist layer 3 is furthersubjected to the exposure process through an unillustrated second maskand the developing process using the developer. The second mask takes ashape suited to effect the exposure over the area corresponding to thelow permeability material portion D in FIG. 4A. Through these processes,the exposed portion on the positive resist layer 3 is removed, andfurther a second′ spatial portion 12 is formed (step 106). The lowpermeability material portion 14 is formed by the electro-depositingprocess in the second′ spatial portion 12 (step 107). Note that theforming thickness of the low permeability material portion 14 islikewise approximately coincident with the thickness of the positiveresist layer 3. The low permeability material portion 14 corresponds, onthe sheet L4, to the low permeability material portion D in FIG. 4A andthe low permeability material portion D in FIG. 4B that is positioned onthe upper surface thereof.

Moreover, the residual unexposed positive resist layer 3 is subjected tothe exposure process through an unillustrated third mask and thedeveloping process using the developer. The third mask has a shapesuited to conducting the exposure over an area corresponding to theconductive material portion A1 in FIG. 4A. Through these processes, theexposed portion on the positive resist layer 3 is removed, and further athird spatial portion 13 is formed (step 108).

A portion 15 composed of the first conductive material is formed by theelectro-depositing process in the third spatial portion 13. Note that inthe present embodiment, when forming the first conductive materialportion 15, the forming thickness thereof is set thinner than thethickness of the positive resist layer 3, and the third spatial portion13 is rendered residual on an upper part of the first conductivematerial portion 15 (step 109). The first conductive material portioncorresponds to the conductive material portion A1 on the sheet L4.

The second layer 17 composed of the positive resist is again formed bythe electro-depositing process on the residual portion of the thirdspatial portion 13 (step 110). On this occasion, it is desirable thatthe second positive resist layer 17 be formed till its uppermost surfaceis substantially flush with the surfaces of the positive resist layer 3,the low dielectric constant material portion 7, etc. The second positiveresist layer 17 undergoes the exposure process through an unillustratedmask and the developing process using the developer. The fourth mask hasa shape suited to conducting the exposure over an area corresponding tothe low permeability material portion D in FIG. 4B. Through theseprocesses, the exposed portion on the second positive resist layer 17 isremoved, and a fourth spatial portion 19 is formed (step 111).

A portion 21 composed of the low permeability material is formed by theelectro-depositing process in the fourth spatial portion 19 (step 112).Note that in the present embodiment, the low permeability materialportion 21 is formed till its uppermost surface is substantially flushwith the surfaces of the positive resist layer 3, the low dielectricconstant material portion 7, etc. The low permeability material portion21 corresponds, on the sheet L4, to the low permeability materialportion D in FIG. 4B. Thereafter, the residual second positive resistlayer 17 is subjected to the exposure process and the developing processusing the developer. Through these processes, the residual secondpositive resist layer 17 is removed, and a fifth spatial portion 23 isformed (step 113).

A portion 25 composed of the second conductive material is formed by theelectro-depositing process in the fifth spatial portion 23. Note that inthe present embodiment, the second conductive material portion 25 isformed till its uppermost surface is substantially flush with thesurfaces of the positive resist layer 3, the low dielectric constantmaterial portion 7, etc. Further, in the present embodiment, thematerial composing the first conductive material portion 15 is the sameas the material composing the second conductive material portion 25. Thesupport body 1 is exfoliated from and the residual positive resist layer3 is removed from the sheet obtained through the steps described above,thereby acquiring the sheet L4 serving as the material when actuallyforming the electronic part. With the aforementioned configurationacquired, it is possible to provide the inductor exhibiting much moreexcellent characteristics than the laminated ceramic inductors in theprior arts have.

According to the present invention, the variety of different materials(portions) can be formed within the same sheet. Hence, the inductor asshown in FIG. 3 can be constructed, and it is feasible to manufacturethe laminated type electronic part that attains further downsizing andhigher integration by decreasing a stray capacitance, a cross-talk andso on. Moreover, though not explicitly illustrated, a wiring layout etc.for connecting a terminal portion of the inductor body to the externalterminal can be arbitrarily arranged round when forming the inductor byuse of the sheet according to the present invention.

Accordingly, optimization of the layout of these wiring portions can befacilitated. Namely, the use of the sheet having the configurationaccording to the present invention acquires effects such as a) an effectenabling the higher integration by improving a degree of freedom of thecircuit design, b) an effect enabling downsizing of the electronic partby, preferably, decreasing the number of laminated layers even whenmanufacturing the electronic part having the equal characteristics onthe occasion of forming composite circuit parts, and c) an effect thatthe wiring connections between the layers are decreased as a concomitantof the reduction in the number of layers, the reliability is improved,and further a decrease in the number of steps till the electronic partis completed can be estimated.

Note that the sheet forming method according to the present inventionhas been discussed so far in depth, however, the variety of materialssuch as the support body described herein are not particularly limited.The support body can involve using a variety of materials such as a thinplate of a stainless group, a PET film with its surface subjected to theconductive process, and a glass substrate with its surface subjected tothe conductive process. Moreover, there is a case of executing a releaseprocess on the surface of the support body, however, the release processis exemplified by forming the surface of mixture composite layers ofNi-PTFE, stainless powder and a Teflon resin or a silicon resin, and soforth.

Further, Ag, Cu, Ni, etc. are usable as metal powders used in theelectro-depositing process for forming the conductive material portion.Though not particularly specified as to the positive resist, it isdesirable that the material be properly selected from a variety ofmaterials, including the selection of the materials such as theconductive material and the insulator, while taking its viscosity,photosensitivity, etc. into consideration. Further, in the sheet formingmethod described above, the formation of the conductive material portionis the formation by the electro-deposition. If there is no necessity offorming a further material, however, this conductive material portionshall be formed by plating as one of the electro-depositing technologiesand may also be composed of only substantially a metal.

Moreover, each portion and the positive resist on the sheet according tothe present invention are subjected to their forming steps by employingthe electro-depositing technology. The present invention is not,however, limited to the electro-depositing technology, and can use avariety of methods employed for forming a normal layer such as coatingthe paste. As described above, however, with respect to forming theconductive material portion, it is considered that there is a case wherethe plating technology etc. is preferable in terms of further enhancingthe conductivity, and it is considered desirable to build up themanufacturing steps so that the conductive material portion can beformed by plating etc.

Moreover, the sheet forming method according to the present inventionacquires the variety of effects given above by using the positiveresist, however, the content of the present invention is not limited tothe embodiment discussed above. For example, when forming the element,the positive resist and the negative resist may be used in combinationin a way that partially applies the pattern formation using the samenegative resist as in the prior arts for the portion which the patternaccuracy etc. is not much requested of.

By the sheet forming method according to the present invention, i.e.,the method of repeatedly executing the exposure process, the developingprocess and the process of forming by the electro-deposition the desiredmaterial in the pattern space obtained by the developing process uponthe positive resist layer, it is possible to obtain the sheet in whichthere are inwardly disposed the portions composed of three or more typesof different materials with the high accuracy in the X-Y direction andthe portions composed of plural types of different materials with thehigh accuracy in the Z direction. Further, the pattern space is formedby executing the exposure process and the developing process on thelayer composed of the single positive resist, thereby obtaining thepattern, wherein the ratio of the thickness to the width of the pattern,which is the so-called aspect ratio, is equal to or larger than 1, 1through 1.5, which is approximately 1.5 through 3 times as large as thevalue in the prior art.

Moreover, according to the present invention, the variety of patternscan be formed with the high accuracy and with the high positionalprecision, and hence there are acquired effects such as a) an effect ofimproving the degree of freedom of the circuit design and enabling thehigher integration, b) an effect enabling a reduction in the totalnumber of the laminated layers owing to the high integration of thecircuit for the single layer of sheet, and enabling the downsizing ofthe electronic part, c) an effect of reducing the connecting portionsbetween the respective layers as a contaminant of the phenomenonpertaining the to the number of the laminated layers, and enabling theimprovement of the reliability or the reduction in the steps, d) aneffect enabling the variety of materials to be formed in the properpositions and enabling the improvement of performance of the laminatedtype electronic part, and e) an effect enabling the improvement of thecost performance in the electronic part manufacturing step owing to astack of these effects.

Still further, the sheet having the high dimensional accuracy isobtained, and hence there are acquired effects such as f) an effect ofimproving the positional precision between the layer-to-later connectingmembers on each sheet, and improving the connection reliability, g) aneffect enabling the smaller-and-smaller shape optimization of thelayer-to-layer connecting member, and enabling the higher integration,and h) an effect capable of making the layer-to-layer connecting memberexist within the sheet having the thickness, improving the degree offreedom as compared with the conventional design etc. taking account ofstrength of the portion related to the layer-to-layer connecting member,and further improving the lamination accuracy owing to handlingstability.

Further, the layer is formed only on the necessary portion by theelectro-depositing process etc., and therefore the manufacturing costcan be reduced without any futility of the materials. Yet further, afterforming the variety of sheets, the electronic part is acquired bylaminating these sheets, and hence the types of the sheets to belaminated or the laminating form etc. can be changed corresponding tothe characteristics requested of the electronic part. Therefore, theelectronic part manufacturing step flexible to more-type less-quantityproductions can be easily built up by use of the sheet according to thepresent invention.

It should be noted that the prior art for executing the patterning andthe electro-depositing process by employing the slurry composed of thepowder exhibiting the desired electrical characteristic and the organicbinder, the slurry being composed of the so-called negative resist, isgreatly inferior to the present invention in terms of the patternaccuracy obtained. It is, however, feasible to partially acquire theeffects given above by employing partially the steps using the positiveresist according to the present invention, corresponding to the accuracyrequested of the product, e.g., an allowable value of scatter in theelectrical characteristic.

1. A sheet forming method of forming a sheet used as each layer whenforming a laminated electronic part, comprising: a step of depositing aphotosensitive substance of which an exposed portion is removed by adeveloper up to a predetermined thickness onto a support body; a step ofexecuting an exposure process for forming a predetermined pattern uponthe photosensitive substance, executing a process fordevelopment-removing the pattern subjected to the exposure process byuse of the developer, executing an electro-depositing process using asubstance having an electrical characteristic onto the portion with thephotosensitive substance removed, and forming said sheet or part of saidsheet on said support body; and a step of removing said support bodyfrom said sheet, wherein said step consisting of the exposure process,the developing process and the electro-depositing process is repeated aplural number of times.
 2. A sheet forming method, of forming a sheetused as each layer when forming a laminated electronic part, comprising:a step of depositing a photosensitive substance of which an exposedportion is removed by a developer up to a predetermined thickness onto asupport body; a step of executing an exposure process for forming apredetermined pattern upon the photosensitive substance, executing aprocess for development-removing the pattern subjected to the exposureprocess by use of the developer, executing a process of depositing asubstance having an electrical characteristic onto the portion with thephotosensitive substance removed, and forming said sheet or part of saidsheet on said support body; and a step of removing said support bodyfrom said sheet, wherein said step consisting of the exposure process,the developing process and the depositing process includes a process ofmaking residual a part of the portion with the photosensitive substanceremoved in a way that stops the depositing process halfway, anddepositing the photosensitive substance in place of the substance havingthe electrical characteristic on the residual part.
 3. A sheet formingmethod of forming a sheet used as each layer when forming a laminatedelectronic part, comprising: a step of depositing a photosensitivesubstance of which an exposed portion is removed by a developer up to apredetermined thickness onto a support body; a step of executing anexposure process for forming a predetermined pattern upon thephotosensitive substance, executing a process for development-removingthe pattern subjected to the exposure process by use of the developer toform a first pattern space, executing a process of depositing a firstsubstance having a first electrical characteristic onto the firstpattern space so that a part of the first pattern space is renderedresidual as a residual portion, depositing a second substance which hasa second electronic characteristic and of which an unexposed portion isremoved by the developer, onto the residual portion, forming a secondpattern space by exposing and developing the second substance,depositing first, second, or other substance into the second patternspace, and thus forming said sheet or part of said sheet on said supportbody; and a step of removing said support body from said sheet.